The activator is for exactly what its name implies; activating the code. Most games will have an activator code made for it. An activator code will always be an "If" codetype. Basically, "If this value at this address is equal to *button value*, trigger code below. A switch code line (CC000000 00000000) switches a code on or off as long as there is an activator to perform the switch.
In the code Bully gave you, there is no need for a switch, because the activator is placed between the code's default and modified code lines. The default value is the first line. When activated or in layman's terms, when the button is pressed, the default value will change to the modified value (60000000 / NOP), which I'm sure you know what that means, as you've programmed in machine code before. I'm not exactly sure what function the code is modifying in the game though. However, the code is basically just doing a user-controlled loop. The line E0000000 80008000 is a terminator. It terminates the code execution. Just like back in the day, like in BASIC and other languages, you would have an "END" statement; this is pretty much the same thing. Without it, problems may arise and you may be trapped in a perpetual loop.
What the code Bully made does is:
Line 1: Value is default
Line 2: If button pressed, go to next line of code
Line 3: If previous statement (button pressed) is true, go to next line
Line 4: End code
Then when the button is pressed a second time, the code will start from Line 1, basically looping over. Since the value is different to the default, Line 1 will activate and the address now has the default value. The process then repeats itself.
Now, onto doing what you have to to get the code working.
Find the button activator for your region for the game. I assume you are PAL region, so the button activator for PAL is below.
283457E2 YYYYZZZZ
But you might be wondering what you need to do with the YYYYZZZZ.
Simple! These are called placeholders. They hold the place for a value, hence the name.
Go to this website: http://geckocodes.org/index.php?arsenal=2
Here you can choose which button you'd like to use for your activator. You said you wanted to map the
to the
, so take the value of the
button and paste it into the activator I showed you above. Now, I assume how the code works is that whenever you press the
button, the game will make you accelerate instead of doing whatever the
button originally made you do.
Try this out and see if the code works to your son's greatest of benefit. If it doesn't, let us know and we will see what we can do.